Online courses for the ham radio license exams.
 

Extra Class Exam Question Pool

effective 7/01/2016 thru 6/29/2020

Show:
    Unseen questions
    Weak questions
    Review questions
    Learned questions
    Incorrect answer choices  
   

Topic 2016-E4: Amateur Practices


2016-E4A: Test equipment: analog and digital instruments; spectrum and network analyzers, antenna analyzers; oscilloscopes; RF measurements; computer aided measurements

2016-E4A01: Which of the following parameter determines the bandwidth of a digital or computer-based oscilloscope?

Sampling rate

Input capacitance

Input impedance

Sample resolution



2016-E4A02: Which of the following parameters would a spectrum analyzer display on the vertical and horizontal axes?

RF amplitude and frequency

RF amplitude and time

SWR and frequency

SWR and time



2016-E4A03: Which of the following test instruments is used to display spurious signals and/or intermodulation distortion products in an SSB transmitter?

A spectrum analyzer

A wattmeter

A logic analyzer

A time-domain reflectometer



2016-E4A04: What determines the upper frequency limit for a computer soundcard-based oscilloscope program?

Analog-to-digital conversion speed of the soundcard

Amount of memory on the soundcard

Q of the interface of the interface circuit

All of these choices are correct



2016-E4A05: What might be an advantage of a digital vs an analog oscilloscope?

All of these choices are correct

Automatic amplitude and frequency numerical readout

Storage of traces for future reference

Manipulation of time base after trace capture



2016-E4A06: What is the effect of aliasing in a digital or computer-based oscilloscope?

False signals are displayed

All signals will have a DC offset

Calibration of the vertical scale is no longer valid

False triggering occurs



2016-E4A07: Which of the following is an advantage of using an antenna analyzer compared to an SWR bridge to measure antenna SWR?

Antenna analyzers do not need an external RF source

Antenna analyzers automatically tune your antenna for resonance

Antenna analyzers display a time-varying representation of the modulation envelope

All of these choices are correct



2016-E4A08: Which of the following instrument would be best for measuring the SWR of a beam antenna?

An antenna analyzer

A spectrum analyzer

A Q meter

An ohmmeter



2016-E4A09: When using a computer's soundcard input to digitize signals, what is the highest frequency signal that can be digitized without aliasing?

One-half the sample rate

The same as the sample rate

One-tenth the sample rate

It depends on how the data is stored internally



2016-E4A10: Which of the following displays multiple digital signal states simultaneously?

Logic analyzer

Network analyzer

Bit error rate tester

Modulation monitor



2016-E4A11: Which of the following is good practice when using an oscilloscope probe?

Keep the signal ground connection of the probe as short as possible

Never use a high impedance probe to measure a low impedance circuit

Never use a DC-coupled probe to measure an AC circuit

All of these choices are correct



2016-E4A12: Which of the following procedures is an important precaution to follow when connecting a spectrum analyzer to a transmitter output?

Attenuate the transmitter output going to the spectrum analyzer

Use high quality double shielded coaxial cables to reduce signal losses

Match the antenna to the load

All of these choices are correct



2016-E4A13: How is the compensation of an oscilloscope probe typically adjusted?

A square wave is displayed and the probe is adjusted until the horizontal portions of the displayed wave are as nearly flat as possible

A high frequency sine wave is displayed and the probe is adjusted for maximum amplitude

A frequency standard is displayed and the probe is adjusted until the deflection time is accurate

A DC voltage standard is displayed and the probe is adjusted until the displayed voltage is accurate



2016-E4A14: What is the purpose of the prescaler function on a frequency counter?

It divides a higher frequency signal so a low-frequency counter can display the input frequency

It amplifies low level signals for more accurate counting

It multiplies a higher frequency signal so a low-frequency counter can display the operating frequency

It prevents oscillation in a low-frequency counter circuit



2016-E4A15: What is an advantage of a period-measuring frequency counter over a direct-count type?

It provides improved resolution of low-frequency signals within a comparable time period

It can run on battery power for remote measurements

It does not require an expensive high-precision time base

It can directly measure the modulation index of an FM transmitter






2016-E4B: Measurement technique and limitations: instrument accuracy and performance limitations; probes; techniques to minimize errors; measurement of "Q"; instrument calibration; S parameters; vector network analyzers

2016-E4B01: Which of the following factors most affects the accuracy of a frequency counter?

Time base accuracy

Input attenuator accuracy

Decade divider accuracy

Temperature coefficient of the logic



2016-E4B02: What is an advantage of using a bridge circuit to measure impedance?

It is very precise in obtaining a signal null

It provides an excellent match under all conditions

It is relatively immune to drift in the signal generator source

It can display results directly in Smith chart format



2016-E4B03: If a frequency counter with a specified accuracy of +/- 1.0 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?

146.52 Hz

165.2 Hz

14.652 kHz

1.4652 MHz



2016-E4B04: If a frequency counter with a specified accuracy of +/- 0.1 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?

14.652 Hz

0.1 MHz

1.4652 Hz

1.4652 kHz



2016-E4B05: If a frequency counter with a specified accuracy of +/- 10 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?

1465.20 Hz

146.52 Hz

10 Hz

146.52 kHz



2016-E4B06: How much power is being absorbed by the load when a directional power meter connected between a transmitter and a terminating load reads 100 watts forward power and 25 watts reflected power?

75 watts

100 watts

125 watts

25 watts



2016-E4B07: What do the subscripts of S parameters represent?

The port or ports at which measurements are made

The relative time between measurements

Relative quality of the data

Frequency order of the measurements



2016-E4B08: Which of the following is a characteristic of a good DC voltmeter?

High impedance input

High reluctance input

Low reluctance input

Low impedance input



2016-E4B09: What is indicated if the current reading on an RF ammeter placed in series with the antenna feed line of a transmitter increases as the transmitter is tuned to resonance?

There is more power going into the antenna

There is possibly a short to ground in the feed line

The transmitter is not properly neutralized

There is an impedance mismatch between the antenna and feed line



2016-E4B10: Which of the following describes a method to measure intermodulation distortion in an SSB transmitter?

Modulate the transmitter with two non-harmonically related audio frequencies and observe the RF output with a spectrum analyzer

Modulate the transmitter with two non-harmonically related radio frequencies and observe the RF output with a spectrum analyzer

Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a peak reading wattmeter

Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a logic analyzer



2016-E4B11: How should an antenna analyzer be connected when measuring antenna resonance and feed point impedance?

Connect the antenna feed line directly to the analyzer's connector

Loosely couple the analyzer near the antenna base

Connect the analyzer via a high-impedance transformer to the antenna

Loosely couple the antenna and a dummy load to the analyzer



2016-E4B12: What is the significance of voltmeter sensitivity expressed in ohms per volt?

The full scale reading of the voltmeter multiplied by its ohms per volt rating will indicate the input impedance of the voltmeter

When used as a galvanometer, the reading in volts multiplied by the ohms per volt rating will determine the power drawn by the device under test

When used as an ohmmeter, the reading in ohms divided by the ohms per volt rating will determine the voltage applied to the circuit

When used as an ammeter, the full scale reading in amps divided by ohms per volt rating will determine the size of shunt needed



2016-E4B13: Which S parameter is equivalent to forward gain?

S21

S11

S12

S22



2016-E4B14: What happens if a dip meter is too tightly coupled to a tuned circuit being checked?

A less accurate reading results

Harmonics are generated

Cross modulation occurs

Intermodulation distortion occurs



2016-E4B15: Which of the following can be used as a relative measurement of the Q for a series-tuned circuit?

The bandwidth of the circuit's frequency response

The inductance to capacitance ratio

The frequency shift

The resonant frequency of the circuit



2016-E4B16: Which S parameter represents return loss or SWR?

S11

S12

S21

S22



2016-E4B17: What three test loads are used to calibrate a standard RF vector network analyzer?

Short circuit, open circuit, and 50 ohms

50 ohms, 75 ohms, and 90 ohms

Short circuit, open circuit, and resonant circuit

50 ohms through 1/8 wavelength, 1/4 wavelength, and 1/2 wavelength of coaxial cable






2016-E4C: Receiver performance characteristics, phase noise, noise floor, image rejection, MDS, signal-to-noise-ratio; selectivity; effects of SDR receiver non-linearity

2016-E4C01: What is an effect of excessive phase noise in the local oscillator section of a receiver?

It can cause strong signals on nearby frequencies to interfere with reception of weak signals

It limits the receiver's ability to receive strong signals

It reduces receiver sensitivity

It decreases receiver third-order intermodulation distortion dynamic range



2016-E4C02: Which of the following portions of a receiver can be effective in eliminating image signal interference?

A front-end filter or pre-selector

A narrow IF filter

A notch filter

A properly adjusted product detector



2016-E4C03: What is the term for the blocking of one FM phone signal by another, stronger FM phone signal?

Capture effect

Desensitization

Cross-modulation interference

Frequency discrimination



2016-E4C04: How is the noise figure of a receiver defined?

The ratio in dB of the noise generated by the receiver to the theoretical minimum noise

The ratio of atmospheric noise to phase noise

The ratio of the noise bandwidth in Hertz to the theoretical bandwidth of a resistive network

The ratio of thermal noise to atmospheric noise



2016-E4C05: What does a value of -174 dBm/Hz represent with regard to the noise floor of a receiver?

The theoretical noise at the input of a perfect receiver at room temperature

The minimum detectable signal as a function of receive frequency

The noise figure of a 1 Hz bandwidth receiver

The galactic noise contribution to minimum detectable signal



2016-E4C06: A CW receiver with the AGC off has an equivalent input noise power density of -174 dBm/Hz. What would be the level of an unmodulated carrier input to this receiver that would yield an audio output SNR of 0 dB in a 400 Hz noise bandwidth?

-148 dBm

-174 dBm

-164 dBm

-155 dBm



2016-E4C07: What does the MDS of a receiver represent?

The minimum discernible signal

The meter display sensitivity

The multiplex distortion stability

The maximum detectable spectrum



2016-E4C08: An SDR receiver is overloaded when input signals exceed what level?

The maximum count value of the analog-to-digital converter

One-half the maximum sample rate

One-half the maximum sampling buffer size

The reference voltage of the analog-to-digital converter



2016-E4C09: Which of the following choices is a good reason for selecting a high frequency for the design of the IF in a conventional HF or VHF communications receiver?

Easier for front-end circuitry to eliminate image responses

Fewer components in the receiver

Reduced drift

Improved receiver noise figure



2016-E4C10: Which of the following is a desirable amount of selectivity for an amateur RTTY HF receiver?

300 Hz

100 Hz

6000 Hz

2400 Hz



2016-E4C11: Which of the following is a desirable amount of selectivity for an amateur SSB phone receiver?

2.4 kHz

1 kHz

4.2 kHz

4.8 kHz



2016-E4C12: What is an undesirable effect of using too wide a filter bandwidth in the IF section of a receiver?

Undesired signals may be heard

Output-offset overshoot

Filter ringing

Thermal-noise distortion



2016-E4C13: How does a narrow-band roofing filter affect receiver performance?

It improves dynamic range by attenuating strong signals near the receive frequency

It improves sensitivity by reducing front end noise

It improves intelligibility by using low Q circuitry to reduce ringing

All of these choices are correct



2016-E4C14: What transmit frequency might generate an image response signal in a receiver tuned to 14.300 MHz and which uses a 455 kHz IF frequency?

15.210 MHz

13.845 MHz

14.755 MHz

14.445 MHz



2016-E4C15: What is usually the primary source of noise that is heard from an HF receiver with an antenna connected?

Atmospheric noise

Detector noise

Induction motor noise

Receiver front-end noise



2016-E4C16: Which of the following is caused by missing codes in an SDR receiver's analog-to-digital converter?

Distortion

Overload

Loss of sensitivity

Excess output level



2016-E4C17: Which of the following has the largest effect on an SDR receiver's linearity?

Analog-to-digital converter sample width in bits

CPU register width in bits

Anti-aliasing input filter bandwidth

RAM speed used for data storage






2016-E4D: Receiver performance characteristics: blocking dynamic range; intermodulation and cross-modulation interference; 3rd order intercept; desensitization; preselector

2016-E4D01: What is meant by the blocking dynamic range of a receiver?

The difference in dB between the noise floor and the level of an incoming signal which will cause 1 dB of gain compression

The minimum difference in dB between the levels of two FM signals which will cause one signal to block the other

The difference in dB between the noise floor and the third order intercept point

The minimum difference in dB between two signals which produce third order intermodulation products greater than the noise floor



2016-E4D02: Which of the following describes two problems caused by poor dynamic range in a communications receiver?

Cross-modulation of the desired signal and desensitization from strong adjacent signals

Oscillator instability requiring frequent retuning and loss of ability to recover the opposite sideband

Cross-modulation of the desired signal and insufficient audio power to operate the speaker

Oscillator instability and severe audio distortion of all but the strongest received signals



2016-E4D03: How can intermodulation interference between two repeaters occur?

When the repeaters are in close proximity and the signals mix in the final amplifier of one or both transmitters

When the repeaters are in close proximity and the signals cause feedback in the final amplifier of one or both transmitters

When the signals from the transmitters are reflected out of phase from airplanes passing overhead

When the signals from the transmitters are reflected in phase from airplanes passing overhead



2016-E4D04: Which of the following may reduce or eliminate intermodulation interference in a repeater caused by another transmitter operating in close proximity?

A properly terminated circulator at the output of the transmitter

A band-pass filter in the feed line between the transmitter and receiver

A Class C final amplifier

A Class D final amplifier



2016-E4D05: What transmitter frequencies would cause an intermodulation-product signal in a receiver tuned to 146.70 MHz when a nearby station transmits on 146.52 MHz?

146.34 MHz and 146.61 MHz

146.88 MHz and 146.34 MHz

146.10 MHz and 147.30 MHz

173.35 MHz and 139.40 MHz



2016-E4D06: What is the term for unwanted signals generated by the mixing of two or more signals?

Intermodulation interference

Amplifier desensitization

Neutralization

Adjacent channel interference



2016-E4D07: Which describes the most significant effect of an off-frequency signal when it is causing cross-modulation interference to a desired signal?

The off-frequency unwanted signal is heard in addition to the desired signal

A large increase in background noise

A reduction in apparent signal strength

The desired signal can no longer be heard



2016-E4D08: What causes intermodulation in an electronic circuit?

Nonlinear circuits or devices

Too little gain

Lack of neutralization

Positive feedback



2016-E4D09: What is the purpose of the preselector in a communications receiver?

To increase rejection of unwanted signals

To store often-used frequencies

To provide a range of AGC time constants

To allow selection of the optimum RF amplifier device



2016-E4D10: What does a third-order intercept level of 40 dBm mean with respect to receiver performance?

A pair of 40 dBm signals will theoretically generate a third-order intermodulation product with the same level as the input signals

Signals less than 40 dBm will not generate audible third-order intermodulation products

The receiver can tolerate signals up to 40 dB above the noise floor without producing third-order intermodulation products

A pair of 1 mW input signals will produce a third-order intermodulation product which is 40 dB stronger than the input signal



2016-E4D11: Why are third-order intermodulation products created within a receiver of particular interest compared to other products?

The third-order product of two signals which are in the band of interest is also likely to be within the band

The third-order intercept is much higher than other orders

Third-order products are an indication of poor image rejection

Third-order intermodulation produces three products for every input signal within the band of interest



2016-E4D12: What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?

Desensitization

Quieting

Cross-modulation interference

Squelch gain rollback



2016-E4D13: Which of the following can cause receiver desensitization?

Strong adjacent channel signals

Audio gain adjusted too low

Audio bias adjusted too high

Squelch gain misadjusted



2016-E4D14: Which of the following is a way to reduce the likelihood of receiver desensitization?

Decrease the RF bandwidth of the receiver

Raise the receiver IF frequency

Increase the receiver front end gain

Switch from fast AGC to slow AGC






2016-E4E: Noise suppression: system noise; electrical appliance noise; line noise; locating noise sources; DSP noise reduction; noise blankers; grounding for signals

2016-E4E01: Which of the following types of receiver noise can often be reduced by use of a receiver noise blanker?

Ignition noise

Broadband white noise

Heterodyne interference

All of these choices are correct



2016-E4E02: Which of the following types of receiver noise can often be reduced with a DSP noise filter?

All of these choices are correct

Broadband white noise

Ignition noise

Power line noise



2016-E4E03: Which of the following signals might a receiver noise blanker be able to remove from desired signals?

Signals which appear across a wide bandwidth

Signals which are constant at all IF levels

Signals which appear at one IF but not another

Signals which have a sharply peaked frequency distribution



2016-E4E04: How can conducted and radiated noise caused by an automobile alternator be suppressed?

By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads

By installing filter capacitors in series with the DC power lead and a blocking capacitor in the field lead

By installing a noise suppression resistor and a blocking capacitor in both leads

By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field lead



2016-E4E05: How can noise from an electric motor be suppressed?

By installing a brute-force AC-line filter in series with the motor leads

By installing a high pass filter in series with the motor's power leads

By installing a bypass capacitor in series with the motor leads

By using a ground-fault current interrupter in the circuit used to power the motor



2016-E4E06: What is a major cause of atmospheric static?

Thunderstorms

Solar radio frequency emissions

Geomagnetic storms

Meteor showers



2016-E4E07: How can you determine if line noise interference is being generated within your home?

By turning off the AC power line main circuit breaker and listening on a battery operated radio

By checking the power line voltage with a time domain reflectometer

By observing the AC power line waveform with an oscilloscope

By observing the AC power line voltage with a spectrum analyzer



2016-E4E08: What type of signal is picked up by electrical wiring near a radio antenna?

A common-mode signal at the frequency of the radio transmitter

An electrical-sparking signal

A differential-mode signal at the AC power line frequency

Harmonics of the AC power line frequency



2016-E4E09: What undesirable effect can occur when using an IF noise blanker?

Nearby signals may appear to be excessively wide even if they meet emission standards

Received audio in the speech range might have an echo effect

The audio frequency bandwidth of the received signal might be compressed

FM signals can no longer be demodulated



2016-E4E10: What is a common characteristic of interference caused by a touch controlled electrical device?

All of these choices are correct

The interfering signal sounds like AC hum on an AM receiver or a carrier modulated by 60 Hz hum on a SSB or CW receiver

The interfering signal may drift slowly across the HF spectrum

The interfering signal can be several kHz in width and usually repeats at regular intervals across a HF band



2016-E4E11: Which is the most likely cause if you are hearing combinations of local AM broadcast signals within one or more of the MF or HF ham bands?

Nearby corroded metal joints are mixing and re-radiating the broadcast signals

The broadcast station is transmitting an over-modulated signal

You are receiving sky wave signals from a distant station

Your station receiver IF amplifier stage is defective



2016-E4E12: What is one disadvantage of using some types of automatic DSP notch-filters when attempting to copy CW signals?

A DSP filter can remove the desired signal at the same time as it removes interfering signals

Any nearby signal passing through the DSP system will overwhelm the desired signal

Received CW signals will appear to be modulated at the DSP clock frequency

Ringing in the DSP filter will completely remove the spaces between the CW characters



2016-E4E13: What might be the cause of a loud roaring or buzzing AC line interference that comes and goes at intervals?

All of these choices are correct

Arcing contacts in a thermostatically controlled device

A defective doorbell or doorbell transformer inside a nearby residence

A malfunctioning illuminated advertising display



2016-E4E14: What is one type of electrical interference that might be caused by the operation of a nearby personal computer?

The appearance of unstable modulated or unmodulated signals at specific frequencies

A loud AC hum in the audio output of your station receiver

A clicking noise at intervals of a few seconds

A whining type noise that continually pulses off and on



2016-E4E15: Which of the following can cause shielded cables to radiate or receive interference?

Common mode currents on the shield and conductors

Low inductance ground connections at both ends of the shield

Use of braided shielding material

Tying all ground connections to a common point resulting in differential mode currents in the shield



2016-E4E16: What current flows equally on all conductors of an unshielded multi-conductor cable?

Common-mode current

Differential-mode current

Reactive current only

Return current





Color key:
● = Unseen
● = Weak
● = Review
● = Learned
● = Incorrect answer
Previous topic:
2016-E3: Radio Wave Propagation
Back to index:
Extra Class Exam Question Pool
Next topic:
2016-E5: Electrical Principles
Home     What is ham radio?     Which exam to take?     Study tips     Where to take the exam?     Frequency Asked Questions (FAQ)     How to     How much math?     Trouble with practice exams     Feedback     Prices     Ham It Forward     Free Extra course for active volunteer examiners     Refund policy     Privacy policy    Terms and conditions     Bumper sticker     Advertise with us     The Ham band     Rate us     Question pools     Course structure     Survivalists     Documents     facebook     Google+     Contact us     Christina's story     TestOnline     Links

The best study method, customer support, and guarantee in the industry!

A TestOnline website.  Copyright © 1998-, HamTestOnline™.  All rights reserved.